1. Field of the Invention
The present invention relates generally to robotic material handling devices and the like, and more specifically to a machine for stacking a relatively thin and narrow strip of flexible material on a pallet. The machine provides reciprocating action in three mutually orthogonal axes to stack the material to a predetermined width, depth, and height or weight on a pallet or the like.
2. Description of the Related Art
Rubber and other flexible, resilient materials are often formed into relatively thin and narrow elongate strips during an intermediate step of manufacture, for transport and storage prior to modification or manufacture into finished goods (tires, etc.). These strips may be hundreds of feet long, and are often stacked and stored on a conventional pallet of perhaps four feet by four feet in width and depth.
Heretofore, the stacking of such continuous strip material has been done by hand, a task that is boring in its extreme and obviously also extremely labor intensive. While relatively low paid workers are used for such tasks, the salaries and fringe benefits (worker's compensation, etc.) which must be provided, add up to a significant cost for this production step.
Accordingly, a need will be seen for an automated, robotic machine which is capable of accepting such essentially continuous strip material, and handling the material to stack it in a sinusoidal pattern of increasing height on a pallet, to a predetermined height or weight. The machine must be capable of performing the chore with very little human assistance, with such assistance basically comprising the initial feeding of material into the machine and starting the machine as required. All other functions of the machine should be automated for optimum efficiency and consistency in loading the pallets. A discussion of the related art of which the present inventors are aware, and its differences and distinctions from the present invention, is provided immediately below.
U.S. Pat. No. 2,050,053 issued on Aug. 4, 1936 to Julius E. Graf et al., titled "Strip Handling," describes a machine through which a strip of thin, flexible sheet metal passes on rollers. A weighted takeup is provided, so that when the movement of the sheet metal strip is momentarily stopped downstream of the machine, production of the metal strip may continue upstream of the machine with the takeup taking up the metal strip between the production and the stopped portion. The Graf et al. machine cannot stack the material, nor can it turn the material to stack it laterally across an axis normal to a first stacking axis. Also, no automated turning or shutoff is provided by Graf et al., all of which are provided in the present invention.
U.S. Pat. No. 3,913,904 issued on Oct. 21, 1975 to Louis Occhetti, titled "Stacking Machine For Rubber Or The Like Sheet Material," describes a frame with an elevator for adjustably lifting a pallet vertically below the sheet material feed means of the machine. The majority of the disclosure is directed to a machine which cuts off substantially identical lengths of sheet material and lays and stacks each length on the pallet, which is slowly lowered to maintain the same vertical distance between the feed rollers and the top of the stack on the pallet. A portion of the disclosure provides for the continuous feeding, folding, and stacking of a continuous, uncut sheet of material, but no means is provided by Occhetti to arrange alternating layers transversely to one another, as provided by the present machine. This is because the Occhetti machine provides only for the stacking of relatively wide sheet material, rather than the relatively narrow strip material provided for by the present invention. Accordingly, the Occhetti machine cannot provide for lateral movement of the sheet material feeder means, as the width of the sheet material being stacked is substantially equal to the width of the pallet. The present stacking device translates the relatively narrow strip laterally across the width of the pallet during each layer of the stacking operation, to lay the relatively narrow strip evenly across the entire pallet. Moreover, the present machine also provides for the rotation of the pallet for laying each subsequent layer transverse to the layer below for a sturdier and more durable stack, which capability is not needed by the Occhetti machine.
U.S. Pat. No. 5,087,140 issued on Feb. 11, 1992 to J. Herbert Keeton et al., titled "Festooning Machine For Cloth Strips," describes a pneumatically driven oscillating spreader, which reciprocates to deliver the cloth strip in a sinusoidal stack atop a pallet or the like. As the strip is relatively narrow, Keeton et al. provide lateral movement in order to distribute the strip more or less evenly across the pallet. However, Keeton et al. oscillate the pallet laterally to accomplish this, rather than moving the feeder means laterally, as is done with the present invention. Moreover, no means is disclosed to adjust the mechanism to allow for the variation in height of the stack as the stack is built up, nor for the rotation of the pallet in order to allow alternating layers to be built up transversely to one another, as provided by the present invention.
U.S. Pat. No. 5,139,247 issued on Aug. 18, 1992 to Luciano Meschi, titled "High Speed Folding Machine For Elastic Material Bands," describes a machine having a pair of spaced apart rollers which alternatingly pinch the material between each roller and an adjacent fixed structure. The result is an accordion folded material which is stacked beneath and between the rollers. As in the case of the U.S. '904 Patent to Occhetti, the material being handled is relatively wide, so there is no need to provide for lateral positioning of the material in the stack, as in the present invention. Also, no means of rotating the stack to provide for transverse layer orientation is provided by the Meschi machine, as is provided in the present invention.
U.S. Pat. No. 5,445,493 issued on Aug. 29, 1995 to Ray A. Yourgalite et al., titled "Apparatus For Palletizing/Unitizing Easily Compressible Products," describes a machine having input and output conveyors at right angles to one another. A "hand assembly" comprising a series of orthogonally disposed open gates, is used to grasp the material about its edges and lift each layer, so another layer may be placed therebelow. The material being handled must therefore be relatively rigid, as the flexible strip material palletized by the present invention, could not be handled by the Yourgalite et al. machine. Moreover, the Yourgalite et al. machine cannot handle continuous strip material, but is only equipped to handle discrete sections or pieces of material.
Finally, U.S. Pat. No. 5,529,564 issued on Jun. 25, 1996 to Hanspeter Hedinger, titled "Apparatus For Depositing, Guiding And Pressing Material Web Parts To Be Stacked," describes a device having means for grasping or holding each edge of a zig-zag or accordion folded material as it is being folded and stacked. However, the Hedinger machine is only adapted for use with relatively wide sheet material, and no means is provided to translate the mechanism laterally to arrange relatively narrow strip material evenly across a pallet, as in the present invention. The present machine provides for movement of the feed mechanism in three mutually orthogonal axes, unlike the Hedinger or other machines described.
None of the above inventions and patents, taken singly or in combination, is seen to describe the instant invention as claimed.